The present invention relates to the dehydration of food and other material and more particularly to a tray structure used in a dehydration apparatus. Each tray has a platform which is easily removable from the outer wall structure of the tray. The invention also relates to a method of manufacturing the two-piece tray structure.
The dehydration of products such as food is a very old art. Early dehydration was performed through exposure to sunlight and wind. Dehydration has since been conducted using dehydration equipment intended to enhance the process of dehydration. Some dehydration equipment has used natural convection, and other equipment has used forced air. Dehydrators were initially designed with a structure resembling a rectangular counter-top oven. The food support platforms were flat rectangular racks which horizontally slid into the dehydrator enclosure. Several racks were supported inside the dehydrator enclosure upon protrusions extending from the vertical, planar walls of the enclosure. If the food item was too large to fit between dehydrator racks, a user could simply remove one of the upper racks to enlarge the space above a lower rack.
These rectangular dehydrators were found to be quite bulky, and later dehydrators were developed wherein the structure of the rectangular dehydrator enclosure and the structure of the racks were combined in the form of stackable dehydrator trays. The stackable dehydrator trays had an outer wall structure with an air circulation passage to replace the enclosure walls of the rectangular dehydrator. The rectangular dehydrator racks were replaced by food support platforms which were integral with the outer wall structure. Rather than horizontally slide a rectangular rack into the dehydrator enclosure, stackable dehydrator trays actually were the dehydrator enclosure. Because the food support platforms were no longer supported on protrusions extending from the dehydrator enclosure, the trays no longer had to be rectangular. Some stackable dehydrator trays were made having a circular shape. Such later dehydrators include those illustrated in U.S. Pat. Nos. 4,190,965 and 4,536,643, assigned to Alternative Pioneering Systems, Inc.
The previous stackable trays each consist of a single piece of molded plastic, which caused several problems. One problem was that the vertical size of the food to be dehydrated was limited to the vertical distance between tray platforms. This vertical distance in the previous one-piece trays was permanently fixed and was slightly less than the height of the tray. Another problem was that the previous one-piece trays were fairly large and difficult to clean. The one-piece tray design did not allow for separate cleaning of the platform and the wall structure. A third problem was that the previous one-piece trays had to be entirely replaced to change the grate or food platform surface. These problems could not be solved by using sliding trays, because the outer wall structure does not allow horizontal sliding.